Showtime's 'The Big C' Enlists Allison Janney

The Emmy winner will guest star in an episode of the Laura Linney series as a Hollywood producer.

Showtime's The Big C has added another big-name guest star for its upcoming third season.

Four-time Emmy winner Allison Janney (The West Wing) has booked a guest-starring role in the dramedy about a woman living with cancer. Janney will play a successful Hollywood producer who wants to buy Cathy (Laura Linney) and Paul's (Oliver Platt) life rights to adapt their story into a feature film.

The series, which ended its second season with Paul suffering a heart attack and opens with Cathy receiving a good prognosis from her clinical trial, has already enlisted Oscar winner Susan Sarandon to play Joy, a cancer survivor who is using her unique experience to inspire and motivate others. The casting continues the series' history with booking big-name guest stars in roles that significantly impact Cathy's character.

In addition to Sarandon, Janney joins Emmy nominee Victor Garber as guest stars already lined up for season three of The Big C. Garber will appear in the premiere as a foil for Sean (John Benjamin Hickey) when an accidental phone call "leads to a harassing situation."